Regensburg 2025 – wissenschaftliches Programm
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O: Fachverband Oberflächenphysik
O 72: Poster Plasmonics and Nanooptics: Light-Matter Interaction, Spectroscopy
O 72.6: Poster
Mittwoch, 19. März 2025, 18:00–20:00, P2
Size effects on the plasmon resonance in silver cluster anions studied by energy-resolved photoemission — •Norman Iwe1, Klara Raspe1, Franklin Martinez1, Lutz Schweikhard2, Karl-Heinz Meiwes-Broer1,3, and Josef Tiggesbäumker1,3 — 1Institute of Physics, University of Rostock, Germany — 2Institute of Physics, University of Greifswald, Germany — 3Department of Life, Light and Matter, University of Rostock, Germany
Numerous applications ranging from efficient solar cells to cancer treatment profit from the interaction between nanoparticles and light. In the case of metal clusters, one often takes advantage of collective resonances of the valence electrons, which lead to a strong increase of the cross section at a certain wavelength. Previous studies already showed, that the resonance energy can be tuned via size and charge state of the nanoparticles. However, systematic measurements to explore the development of the plasmonic resonance in free metal clusters so far concentrate on small sizes.
We conduct photoelectron spectroscopy on anionic silver clusters AgN− in a size range N = 7 − 300. By extracting photodetachment cross sections, we gain insights into the collective resonances. At N = 55, we observe a transition from a blueshift to a general redshift of the plasmon energies with decreasing cluster size. However, the resonance energies for sizes below N = 55 are oscillating whereby the maxima are found at known electronic shell closures. On top, a splitting of the resonance is observed at a few smaller cluster sizes, hinting on a deformation of the particle.
Keywords: Plasmon; Photoelectron; Cluster; Silver; Cross section